Project Summary Hypertension and its complications including chronic kidney disease (CKD), peripheral vascular disease, stroke and heart disease are a major public health problem. Salt sensitive hypertension affects 50% of hypertensives and is associated with an increased risk for the development of end-organ injury including atherosclerosis, left ventricular hypertrophy and renal disease. Although hypertension, and especially salt sensitive hypertension, is recognized as a major risk factor for CKD and cardiovascular disease, the mechanisms by which hypertension causes end organ injury are not completely understood. Maladaptive activation of RAS plays an important role in the pathogenesis of end organ injury in hypertension by promoting oxidative stress, extracellular matrix deposition, cell proliferation and inflammation. It is not clear whether these effects occur via independent mechanisms, or alternatively, whether common transcriptional mechanisms mediate the activation of multiple pathways that participate in the pathogenesis of end-organ injury in hypertension. The transcription factor ETS-1 has been identified as a critical molecule that regulates the vascular expression of a variety of growth factors, chemokines and adhesion molecules. Our central hypothesis is that ETS-1 is a common transcription factor that mediates the activation of pro-inflammatory and pro-fibrotic pathways involved in the pathogenesis of vascular and renal injury in salt sensitive hypertension. We will test our hypothesis by pursuing the following specific Aims: Aim 1: Characterize the role of NADPH oxidase (NOX) derived ROS as mediators of vascular and renal ETS-1 expression in salt sensitive hypertension. The working hypothesis for this aim is that NADPH oxidase (NOX) derived ROS play a critical role as mediators of ETS-1 expression in salt sensitive hypertension. We will use the following experimental approach to take this aim to completion: 1) We will identify the glomerular and vascular cells that up-regulate ETS-1 in hypertensive salt sensitive rats; 2) We will determine the role of blood pressure lowering on ETS-1 expression in salt sensitive hypertension and 3) We will determine the role of NADPH oxidase derived ROS on ETS-1 expression in salt sensitive rats. Aim 2: To identify the role of ETS-1 as mediator of renal and vascular injury in salt sensitive hypertension. The working hypothesis for this aim is that ETS-1 plays a critical role as mediator of glomerular inflammation and fibrosis in the hypertensive Dahl salt sensitive rat, a paradigm of salt sensitive hypertension in humans. We will use the following experimental approach to take this aim to completion: 1) We will determine the effects of ETS-1 blockade with a specific dominant negative peptide on renal and vascular inflammation and fibrosis in hypertensive Dahl salt sensitive rats and 2) we will determine the effects of ETS-1 blockade on the expression of pro-inflammatory cytokines in hypertensive Dahl salt sensitive rats. Aim #3: Identify the molecular mechanisms by which ETS-1 modulate the expression of pro-inflammatory and pro-fibrotic genes. Our working hypothesis is that ETS-1 is a critical mediator of renal inflammation and fibrosis in response to Ang II and that these effects occur via increased ETS-1 mediated transcription of pro-inflammatory and pro-fibrotic cytokines. We will use the following experimental approach to take this aim to completion: We will determine the effects of ETS-1 on the expression of several pro- inflammatory and pro-fibrotic cytokines and will also determine the transcriptional regulation of MCP-1 and CTGF by ETS-1 in mesangial cells.